Reproduce before you fix

Shell (bash)

%%bash
base=https://academy.cloudtechanalytics.com/datasets/refunds
for f in refunds.py db.py app.py schema.sql customers.csv orders.csv order_items.csv test_refunds.py pytest.ini; do
  curl -sO "$base/$f"
done

Shell (bash)

%%bash
cat > test_issues.py <<'EOF'
from datetime import date

import db
from refunds import item_refund, refund_amount, within_window


# ISSUE-101: one T-shirt pack at N2,499.99 (249,999 kobo), damaged, delivery fee 150,000 kobo
def test_damaged_refund_is_exact_to_the_kobo():
    # 249,999 + 150,000 = 399,999 kobo
    assert refund_amount([(1, 249_999)], "damaged", 150_000) == 399_999


def test_restocking_fee_rounds_half_up():
    # 249,999 x 0.9 = 224,999.1 kobo, which rounds to 224,999
    assert item_refund(1, 249_999, "changed_mind") == 224_999
    # 333,333 x 0.9 = 299,999.7 kobo, which rounds to 300,000
    assert item_refund(1, 333_333, "changed_mind") == 300_000


# ISSUE-103: delivered 1 September; the policy allows returns within 14 days
def test_return_on_day_14_is_allowed():
    assert within_window(date(2026, 9, 1), date(2026, 9, 15))


def test_return_on_day_15_is_refused():
    assert not within_window(date(2026, 9, 1), date(2026, 9, 16))


# ISSUE-104: a search must only ever return the matching customer's orders
def test_email_search_cannot_be_tricked():
    conn = db.connect()
    db.init(conn)
    assert db.find_orders_by_email(conn, "' OR '1'='1") == []
EOF
python -m pytest --tb=no -rf

FFF.F...
=========================== short test summary info ===========================
FAILED test_issues.py::test_damaged_refund_is_exact_to_the_kobo - AssertionEr...
FAILED test_issues.py::test_restocking_fee_rounds_half_up - AssertionError: a...
FAILED test_issues.py::test_return_on_day_14_is_allowed - assert False
FAILED test_issues.py::test_email_search_cannot_be_tricked - assert [<sqlite3...
4 failed, 4 passed in 0.01s

Shell (bash)

%%bash
python - <<'EOF'
from datetime import date

import db
from app import create_app

conn = db.connect()
db.init(conn)
client = create_app(conn, today=date(2026, 9, 20)).test_client()
for part in [{"sku": "POT-SET", "quantity": 2}, {"sku": "BLN-X1", "quantity": 1}]:
    r = client.post("/orders/K-1005/refunds", json={"reason": "damaged", "items": [part]})
    print(r.status_code, r.get_json()["amount_kobo"])
paid = sum(i["quantity"] * i["unit_price_kobo"] for i in db.order_items(conn, "K-1005")) + db.get_order(conn, "K-1005")["delivery_fee_kobo"]
refunded = sum(r["amount_kobo"] for r in db.refunds_for(conn, "K-1005"))
print(f"paid {paid}, refunded {refunded}, over by {refunded - paid}")
EOF

201 5800000
201 4800000
paid 10300000, refunded 10600000, over by 300000